Electric furnace



- March 18, 1930. w. KEENAN 1,751,334

ELECTRIC FURNACE Filed Dec. 27, 1924 William Keenan,

Hi5 A4c tovneg.

Patented Mar. 18, 1930 UNITED STATES PATENT OFFICE WILLIAM KEENAN, OFSCHENECTADY, NEW YORK, ASSIGNOR '10 GENERAL ELECTRIC COMPANY, ACORPORATION OF NEW YORK ELECTRIC If.-UIlEtIl l'AQIEl Application filedDecember 27, 1924. Serial No. 758,473.

resistor in such manner that heat is radiated directly therefrom intothe heating chamber.

My invention relates more specifically to means for supportingresistance heating units or resistors of the type comprising a pluralityof horizontally extending self-supporting convolutions, such asdescribed and claimed in U. S. Patent No. 1,432,442 to C01- lins datedOctober 17, 1922. Such heating units are self-supporting and maytherefore be upheld by suitable means cooperating with the extremitiesonly of the convolutions. In the Collins patent a single resistor isshown, this resistor extending across the furnace chamber and beingsupported at the side walls. My inventionhas particular applica- :tionto furnaces in which it is impracticable for various reasons, such asrelatively great width of the heating chamber, to use a single resistorextending from side to side of the heating chamber. F or example; in arelatively wide furnace it may be necessary to use a plurality ofcomparatively narrow resistors in order that the resistors may havesufficient rigidity to be self-supporting.

In carrying out my invention 1 provide supporting means for the resistorcomprising a plurality of pins which are removably secured in speciallyconstructed bricks built in the roof of the furnace. With thisconstruction, the resistor may be easily and quickly put in place, andit is free to expand and contract by reason of the freedom of the pins.

' Moreover, radiation of heat from the resistor end elevation viewpartly in section of an electric furnace embodying my invention; Fig. 2is an enlarged fragmentary plan view of Fig. 1. Fig. 8 is an enlargeddetail view by spacing bricks.

of the supporting means; while Fig. 4 is a plan view of the resistor.

Referring to the drawing,.l[ have shown my invention in one form as usedfor supporting a heating resistor from the roof of the furnace, althoughit obviously may have other applications. The side walls and bottom ofthe furnace heatin chamber 10 are formed by heat refractory bricks 11and the roof, which may be slightly arched, is constructed fromwedge-shaped heat refractory bricks 12. Enclosing the whole is a layerofheat insulating bricks 13.

Rows 14 of specially constructed heat refractory bricks 15 are built inthe roof of the furnace. These bricks 15 may be placed side by side inengagement with each other in the rows 14 as shown, or they, may beseparated They support metallic pins 16 which project downward into theheating chamber and in turn form hangers for resistance heating units orresistors 17, 1 8 and 19. The rows of specially constructed bricks arespaced apart in pairs and each pair of rows carries the pins on which aresistor is mounted. Each resistor extends back and forth in zig-zagformation between the rows of bricks from which it is supported andtherefore takes the form of a plurality of integral, end connected,substantially parallel extending straight convolutions which arerelatively heavy so as to be self supporting between the pin sup orts.The resistors are made from a suita le electrical resistance heatingmaterial, such as a nickel-chromium alloy, and the pins 16 may be madefrom the same material.

As shown, three pairs of rows of specially constructed bricks are builtin the roof whereby the three heating resistors 17, 18 and 19 aresupported. These resistors may extend substantially the full length ofthe heating chamber.

The construction of the bricks 15 is shown in detail in Fig. 3. A recess20 is provided on one side. of each brick at its lower end. As viewedfrom the side of the brick this recess is rectangular in shape andsomewhat deeper than the diameter of pins 16. At the upper end of thisrecess is a transversely extending inner recess 21 which is L shaped toprovide a depression or notch 22. It will be understood that the sideopening of recess 20 is closed by the adjacent brick 15 so that therecess 20'is open only at the bottom. This bottom opening23 has itsgreater dimension extending crosswise of the row 14 whereby the pins 16are free to move in recesses 20 to provide for expansion and contractionof the resistor. v

A short portion 24 on -the' upper end of each pin 16 is bent over atright angles. After the bricks 15 have been built into the furnace wall,the pins are inserted through the openings 23-. After insertion, eachpin is turned through a quarter revolution until the end portion 24 liesin the inner recess 21, and the pin is then adjusted sideways until thisend portion falls into the notch '22, whereby the pin is secured inplace in interlocking relation with the furnace wall. It will beobserved, however, that by raising the ins out of notches 22 and turningthem in t e reverse direction through a quarter revolution, they may beremoved.

Suitable hooks 25v are provided on the lower ends of the pins in whichthe bends of the zigzag resistor are placed whereby it will be observedeach length or convolution of the resistoris supported by two hooks, one

. at each end. Preferably the shank of the ,pin extendsthrough the loopof the resistor,

' the end of the hook'being on the outside.

As shown the resistor is made from a ribbon which is preformed or bentbefore installation in such manner that it is supported edgewise, i. e.with the greater sectional dimension of the ribbon extending vertically,This gives the resistor suflicient rigidity to prevent sagging when hot.The resistor may, however, be cast with the desired configuration. Asshown in Fig. 4 the resistors 17, 18 and 19 may have a common connection26 so that they may be operated on a threephase source of supply. Theterminals 27, 28, and 29 of the resistors may be brought out throughsuitable bushings in the furnace roof for connection with the source ofembodied in concrete form and as operating in a specific manner inaccordance with the provisions of thespatent statutes, it should beunderstood that I do not limit my invention thereto, since variousmodifications thereof will suggest themselves to those skilled in theart without departing from the spirit of my invention, the scope ofwhich is set forth in'the annexed claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. An electricvfurnace comprising a heating chamber enclosed by wallsformed of heat refractory material, a plurality of metallic pinsremovably interlocked with one of said walls so as to project endwiseinto said heating chamber, and a sinuous heating resistor in saidchamber mounted .on said pins in spaced relation to said heat refractorymaterial.

2. An electric furnace comprising a heatingv .chamber provided with aroof con structed of heat refractory material, a plurality of metallicpins removably secured in spaced relation to said roof so as to projectendwise downward into said heating chamber, and a sinuous heatingresistor in said chamber having its convolutions mounted inacubstantially horizontal position on said ins.

3. An electric furnace comprising a heating chamber having a roofconstructed of heat refractory material provided with recesses, aplurality of metallic pins in said recesses removably interlocked withthe walls of said recesses so as to project endwise downward into saidheating chamber, hooks on the lower ends of said pins, and a sinuous,preformed, self-supporting heating resistor in said chamber having itsconvolutions resting in a substantially horizontal position on saidhooks.

4. An electric furnace comprising a heating chamber provided with a roofformed of heat refractory material, heat refractory bricks'provided'withrecesses built into said roof, metallic pins removably secured in saidrecesses so as to project endwise into said heating chamber, and apreformed self-supporting heating resistor provided with a plurality ofhorizontally extending convolutions mounted directly on said pins inspaced relation to said roof.

5. Means for supporting a heating resistor in a furnace chamber,comprising heat refractory bricks provided with recesses built in theroof of the furnace chamber, and pins forming hangers for the resistorinserted endwise into said recesses so as to hang downward into saidchamber in substantially vertical positions, said pins being providedwith locking means engaging the Walls of said recesses so as todetachably secure the pins therein.

6. Means for supporting a heating resistor in. a furnace chambercomprising heat refractory' bricks built-in the roof of the furnacechamber, said bricks being each provided with an outer recess and aninner trans versely extending recess, and metallic pins greases havingprojections inserted in said outer recesses and secured by turning saidpro ections into sa d inner recesses, said pins forming hangers for theresistor.

bricks built in said roof, said bricks being each provided with an outerrecess and an inner transversely extending recess, metallic pins havingprojections inserted in said outer recesses and secured by turning saidprojections into said inner recesses, and a sinuous heating resistorsupported by said pins.

9. An electric furnace comprising walls forming a heating chamberprovided with a roof formed of heat refractory material, heat refractorybricks laid in said roof, said bricks being eac provided with an outerrecess having an elongated, transverse section, and an innertransversely extending recess, metallic pins inserted in said outerrecesses having end portions bent at right angles, said pins beinglocked by turning said right angle portions into said inner recesses,and a sinuous heating resistor supported by said pins.

10. An electric furnace comprising a heating chamber provided with aroof formed of heat refractory material, heat refractory bricks built insaid roof, said bricks being each provided with an outer recess and aninner transversely extending recess of irregu lar shape to provide anotch, and metallic 'fso pins inserted in said recesses havingendportions bent at right angles, said pins being detachably locked byturning said end portions into said inner recesses and seating said endportions in said notches, and a sinuous heating resistor supported bysaid pins.

11. An electric furnace comprising a heating chamber provided with aroof formed of heat refractor material, two rows of heat refractory bries provided with recesses built in said roof, pins inserted in saidrecesses provided withlocking means engaging the walls of said recessesso as to secure the pins therein, and a heating resistor extending backand forth between said rows of bricks and sup ported at its bends bysaid pins inspaced relation with said roof;

- 12. An electric furnace comprising a heating chamber provided with aroof formed of heat refractory material, two rows of heat refractorybriclc's, having recesses built in said roof, pins inserted in saidrecesses provided with locking means engagin the walls of said recessesso as to detaeha ly securethe pins therein, and a ribbon-shaped heatingresistor bent insZig-Ztig' conformation between said rows of bricks intoa plurality of edge- Wise convolutions and supported at its bends onsaid pins.

13. Means for supporting a heating resistor in a furnace chambercomprising a plurality of pins forming hangers for the resistorpivotally secured to the roof of the furnace chamber so as to movefreely with the resistor upon expansion and contraction thereof.

14. Means for supporting a heating resistor in a furnace chambercom-prising heat refractory bricks provided with recesses built in theroof of the furnace chamber, and pins forming hangers for the resistorsecured in said recesses so as to move freely with the resistor uponexpansion and contraction thereof.

15. An electric furnace comprising a heating chamber, a plurality ofpins pivotally secured to the roof of said heating chamber, and asinuous heating resistor mounted on said pins provided with a pluralityof lengths extending substantially in the directions of the swinging ofsaid pins whereby said resistor is free to expand and contractindependently of said roof.

16. An electric furnace comprising a heating chamber having a roofconstructed of heat refractory material provided with elongatedrecesses, a plurality of pins pivotally secured in said recesses so asto be free to swing there in, and a heating resistor mounted on saidpins'provided with a plurality of lengths extending substantially in thedirections of saidrec'esses whereby said lengths are free to expand andcontract independently of said room.

17. An electric furnace comprising a heating chamber provided with aroof formed of heat refractory material, heat refractory bricks providedwith elongated recesses built into said roof, a plurality of pins havingend portions bent at right angles secured in said recesses so as to befree to swing on said end portions, and a heating resistor mounted onsaid pins provided with a plurality -of lengths extending substantiallyin the direction of said recesses whereby said resistor is free toexpand and contract independently of said roof by the swinging of saidpins in said recesses.

18. An electric furnace comprising a heating chamber provided with aroof formed of heat refractory material, heat refractory bricks built insaid roof, said bricks being each provided with an outer elongatedrecess and an inner transversely extending recess, metallic pinsinserted in said recesses having end portions bent at right angles, saidpins being detachably locked by turning said end portions into saidinner recesses whereby said pins are free to swing on said-end portionsin said elongated recesses, and a heating resistor mounted on said pinsprovided with a plurality of spaced convolutions extending substantiallyin the directions in which said pins are free to swing, whereby saidresistor is free to expand and contract independently of said roof.

19. In an electric furnace, in combination, a preformed, relativelyheavy resistor member comprising a plurality'of end-connectedsubstantially parallel-extending straight convolutions, and a pluralityof spaced hook members removably mounted in and interlocked with a wallof said furnace for supporting said resistor member.

20. In an electric furnace, in combination, a plurality of refractorywalls enclosing a furnace chamber, a plurality of spaced sets of hookssupported in spaced relation relatively to each other in one of saidwalls, said hooks being removably mounted in and interlocked with one ofsaid walls, and a relatively heavy resistor member preformed to comprisea plurality of substantially parallelextending straight convolutions,each of said convolutions being supported by at least two of said hooks.I

21. In an electric furnace, in combination, a plurality of refractorywalls enclosing a furnace chamber, a relatively heavy resistor memberpreformed to comprise a plurality of integral,end-connected-substantially parallel-extending, straight convolutions,and a plurality of spaced hooks for releasably supporting said resistormember, said hooks being so mounted in one of said Walls as to beremovable therefrom by a turning movement relatively thereto.

22. In an electric furnace, in combination, a plurality of refractorywalls enclosing a' furnace chamber, a relatively heavy resistor memberpreformed to comprise a plurality of end-connected, integral,substantially parallel-extending, straight, convolutions and a pluralityof hook members, removably supported by one of said walls andinterlocked therewith, for operatively engaging said convolutions atspaced points to support said resistor in its operative position in saidfurnace chamber.

23. An electric furnace comprising walls forming a heating chamber, oneof said walls being provided with recesses each including an innertransversely extending recess, pins in said recesses, said pins beingprovided with projections extending into said transversely extendingrecesses so as to removably interlock said pins with said'wall, and asinuous heating resistor supported by said pins.

24:. An electric furnace comprising heat vided with locking meansengaging the-walls of said recesses so as to removably secure the pinstherein, and a heating resistor extending back and forth between saidpins and supported by said pins in spaced relation with said wall.

In witness whereof, I have hereunto set my hand this 26th da ofDecember, 1924. WI LIAM KEENAN.

refractory walls forming a heating chamber,

one of said walls being provided with two rows of recesses, pins 1I1S&1d recesses pro-

